METEORITE LANDINGS
An exploration of NASA's Meteorite Landings dataset[data]em>
"A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon."[1]
The visualization below shows all known meteorite landings from the Metorical Society since 1800.[2] The year indicated is the year that the meteorite fell or was found - indicated by color. A "found" meteorite may have fallen many years prior to when it was found. For example, the largest meteorite found is the Hoba meteorite at 60,000 kg (132,277 lbs). It was found in 1920, but is believed to have landed around 80,000 years ago.[3] See if you can find it on the map below!
Starting in 1974, there has been a huge increase in discovered meteorites with a record 3,045 being found in 1979! While the increase has been significant since before 1974, there are only weak signs of growth in later years with a weak correlation coefficient of 0.29 from 1974 - 2013.
The boxlot below shows us the typical mass (in grams) of the meteorites that have been found. After removing the many outliers (indicated by the + sign) the median meteorite size is about 17 grams with the typical meteorite weighing between 1 and about 251 grams. Most meteorites are harmless and anything that is typically big enough to cause major damage would be an outlier!
The most frequent class of meteorite to be found has the L6 classification. What does this mean?
According to the Meteorical Society this means it has the following specifications:
"Ordinary chondrite: A major class of chondrites, distinguished by sub-solar Mg/Si and refractory/Si ratios, oxygen isotope compositions that plot above the terrestrial fractionation line, and a large volume percentage of chondrules, with only 10-15 vol% fine-grained matrix.
L group: The low-iron (L) chemical group of ordinary chondrites, distinguished by their relatively low siderophile element content, moderate sized chondrules (~0.7 mm), and oxygen isotope compositions that intermediate between H and LL group ordinary chondrites.
type 6: Designates chondrites that have been metamorphosed under conditions sufficient to homogenize all mineral compositions, convert all low-Ca pyroxene to orthopyroxene, coarsen secondary phases such as feldspar to sizes ≥50 µm, and obliterate many chondrule outlines; no melting has occurred."[4]
Some environments make it naturally easier to find meteorites. Some of the best places to find meteorites are in deserts, both hot and cold. According to Washington University in St. Louis, 62.2% of meteorites are found in Antarctica, a cold desert.[5] In the heatmap you can see that many of the biggest hotspots are in Antarctica. In these environments the meteorites can sit for thousands of years with minimal influence from the elements.
